The Frequency Domain Photon Migration (FDPM) concept can be used to quantitatively determine rapidly and non-invasively the wavelength-dependence of material absorption and scattering in a single measurement. This concept is implemented in instrumentation by using directly modulated high power discrete diode lasers emitting from674 nm to 956 nm. A network analyzer is used to produce a swept sinusoidalsignal (300 kHz to 3 GHz), which is superimposed upon the direct current of the diode laser. The modulated optical signal is applied to the sample and under goes scattering and absorbtion. This information is detected with an optical detector and applied to the input of the network analyzer. A remote computer with a user friendly interface using virtual instrumentation allows for simple and rapid data aquisition and analysis. The data is converted to the absorbtion and effective scattering coefficients ( a and s') which can be used in the detection and monitoring of biological processes.